Dynamic Characteristic And Flow Field Simulation Analysis Of The Large And High-water Based Proportional Direction Valve

Coal mine hydraulic support is an important part of fully mechanized mining face.The accurate and efficient control of the support is directly related to the production efficiency of the whole working face.The reversing valve is the key control element of the hydraulic support.The reversing valve with excellent performance is the basis of ensuring high efficiency coal mining in coal mines.At present,all the directional valves used in hydraulic support of coal mine are switch directional valves.However,with the increase of flow rate and pressure of hydraulic support,the switched directional valves bring huge hydraulic impact to the system at the moment of opening and closing.Thus causing system vibration and component damage.In addition,there is a growing demand for intelligent of coal mines,which requires the hydraulic support to be accurately positioned and accurately adjusted for posture.The simplest and most effective way to solve the above problems is to develop a large flow and high water-base proportional directional valve instead of the existing switch-typereversing valve.This paper introduces the research developments of proportional valve at home and abroad,expounds the difficulties of proportional valve design under the conditions of bad working conditions and high water-based medium in coal mine,analyzes the working mechanism of the existing reversing valve,so the direction of the design is clear and puts forward a scheme which can be applied to the proportional directional valve in the coal mine.The proportional valve consists of the pilot stage and the main valve,and introduces the composition and working principle of the pilot stage and the main valve respectively.The stress of pilot valve and main valve inlet valve core is analyzed,and then it is clear that the parameters such as steady-state flow force and balance cavity dimension and so on are the key to precise control valve core movement.The CFD technology was used to study the valve fluid power,optimize the valve structure size in order to eliminate the valve spring "negative" effects of fluid dynamics,the maximum value of the steady-state flow force 752.773015 N.At the same time,the steady-state flow force mathematical model has fitted out.The simulation results are used to fit out the flow mathematical model of the valve port in full working conditions,so the valve port flow can be calculated by monitoring the displacement of the valve core and the inlet and outlet pressure difference of the valve port.The simulation model of proportional direction valve is built in AMESim simulation software,and the static and dynamic characteristics of the valve areanalyzed.The results show that the main spring stiffness and proportional coefficient k the greater the linearity of the valve,the valve is insensitive to load changes when thebalance cavity diameter is selected 25.3mm.Without PD control,the step response of the valve is slow and the frequency response is low.By introducing PD regulation,the dynamic characteristics of the valve are greatly improved.The step response time is about 0.24 s and the frequency response reaches 19.8Hz.In this paper,a proportional directional valve scheme is put forward under the condition of knowing the requirement and working conditions of the directional valve in coal mine,and the hydraulic control theory,dynamics theory and computer simulation are used to study the scheme.The research results of this paper provide an important reference for the further improvement of the proportional directional valve research.